Field-terminated pre-polished fiber optic connectors include an interface at which two optical fibers, a field optical fiber (“field fiber”) and an internal stub optical fiber (“stub fiber”), are coupled. Such connectors include a pre-polished front face that enables a connection with another compatible fiber optic connector. In such a connector, the stub fiber is essentially disposed between two interfaces: the field fiber-stub fiber interface, and the connector interface with the compatible connector at the pre-polished front face.
Ideally, all of the light energy passing through the core of a single-mode field fiber will continue unimpeded across the interface into the core of the stub fiber in the pre-polished fiber optic connector. In this ideal scenario, the interface between the field fiber and the stub fiber is said to have a coupling efficiency, η1, equal to one, because all light traveling in the core of the field fiber becomes coupled into a primary mode, designated as LP01 for single-mode fibers, and travels through the stub fiber core. But in reality, optical interference effects occur as a result of misalignment of the cores of the field and stub fibers or mismatch of the mode-field diameter (MFD) or optical-power distribution for the field and stub fibers. This misalignment or mismatch excites unwanted higher-order coherent modes, such as the LP11 and LP02 modes for single-mode fibers, which interfere with one another within the short length of the stub fiber. This interference can be constructive or destructive, which, in the latter case, causes an overall increase in insertion loss of the connector interface.
A need exists for a pre-polished quick-terminated fiber optic connector that overcomes these and other problems.